The Joy-Con controllers for the Nintendo Switch are being supported in Steam by Valve. Similar to how you may use Joy-Cons in any configuration for Switch games, they will be supported both alone and in pairs as part of the most recent Steam beta. If you want to test out the feature, you can sign up for the Steam beta. Valve provides detailed instructions on the Steam website. Just make sure your Joy-Cons aren’t wandering.
Although the company didn’t provide specifics in the beta patch notes, Valve is also enhancing the support for the Nintendo classic controllers it sells to Switch Online users. The ability to use NES, SNES, N64, and Sega Genesis controllers designed for the Switch was just added to the public version of the Steam client last week.
Additionally, there are options available if you wish to utilise a controller that isn’t a Nintendo controller with Steam. Soon after the PS5 was released in 2020, Valve added support for the DualSense controller from Sony, and in early 2021, they increased Steam’s support for Xbox controllers.